I use a single-bowl stainless kitchen sink in my darkroom. For film processing, I generally use a tray next to the sink to contain a water bath, film washing happens in the sink. For printing, I set up trays on a counter that's separated from the sink because of the room layout. I have a vertical print washer next to the sink opposite the tray, which drains into the sink, a tray with a syphon drain would work too.
A smaller sink, for example, a typical "bar sink" would work too if you're really constrained for space. IMO what's most important is that the sink has a flat bottom. The depth is not so important (IMO), most bar sinks are probably a bit too deep to be convenient, though they are easy to buy in home centers and such. There are food service handwashing sinks that are pretty small and shallow, but they can be expensive new.